Performance and power management in direction of arrival determination by utilizing sensor information

ABSTRACT

A system for enhancing the performance of a wireless communication device (WCD) while executing a direction of arrival (DoA) estimation. The performance may be improved through device management, and may include the collection of information from one or more sensors installed within the WCD. The sensor information may initially be used to determine an appropriate configuration for the device. Further, the sensor information may also be used to affect the behavior of the device while performing the DoA estimation.

This application is a continuation of co-pending U.S. application Ser.No. 11/532,426, filed Sep. 15, 2006, entitled “PERFORMANCE AND POWERMANAGEMENT IN DIRECTION OF ARRIVAL DETERMINATION BY UTILIZING SENSORINFORMATION”, to which priority is claimed, and which is incorporatedherein by reference in its entirety.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to a system for wireless direction-findingand location, and more specifically, to a system for improving theoverall performance and power management in a wireless communicationdevice performing a direction of arrival estimation.

2. Description of Prior Art

Modern society has quickly adopted, and become reliant upon, handhelddevices for wireless communication. For example, cellular telephonescontinue to proliferate in the global marketplace due to technologicalimprovements in both the quality of the communication and thefunctionality of the devices. These wireless communication devices(WCDs) have become commonplace for both personal and business use,allowing users to transmit and receive voice, text and graphical datafrom a multitude of geographic locations. The communication networksutilized by these devices span different frequencies and cover differenttransmission distances, each having strengths desirable for variousapplications.

Cellular networks facilitate WCD communication over large geographicareas. These network technologies have commonly been divided bygenerations, starting in the late 1970s to early 1980s with firstgeneration (1G) analog cellular telephones that provided baseline voicecommunications, to modern digital cellular telephones. GSM is an exampleof a widely employed 2G digital cellular network communicating in the900 MHz-1.8 GHz band in Europe and at 1.9 GHz in the United States. Thisnetwork provides voice communication and also supports the transmissionof textual data via the Short Messaging Service (SMS). SMS allows a WCDto transmit and receive text messages of up to 160 characters, whileproviding data transfer to packet networks, ISDN and POTS users at 9.6Kbps. The Multimedia Messaging Service (MMS), an enhanced messagingsystem allowing for the transmission of sound, graphics and video filesin addition to simple text, has also become available in certaindevices. Soon emerging technologies such as Digital Video Broadcastingfor Handheld Devices (DVB-H) will make streaming digital video, andother similar content, available via direct transmission to a WCD. Whilelong-range communication networks like GSM are a well-accepted means fortransmitting and receiving data, due to cost, traffic and legislativeconcerns, these networks may not be appropriate for all dataapplications.

Short-range wireless networks provide communication solutions that avoidsome of the problems seen in large cellular networks. Bluetooth™ is anexample of a short-range wireless technology quickly gaining acceptancein the marketplace. A Bluetooth™ enabled WCD transmits and receives dataat a rate of 720 Kbps within a range of 10 meters, and may transmit upto 100 meters with additional power boosting. A user does not activelyinstigate a Bluetooth™ network. Instead, a plurality of devices withinoperating range of each other will automatically form a network groupcalled a “piconet”. Any device may promote itself to the master of thepiconet, allowing it to control data exchanges with up to seven “active”slaves and 255 “parked” slaves. Active slaves exchange data based on theclock timing of the master. Parked slaves monitor a beacon signal inorder to stay synchronized with the master, and wait for an active slotto become available. These devices continually switch between variousactive communication and power saving modes in order to transmit data toother piconet members. In addition to Bluetooth™ other popularshort-range wireless networks include WLAN (of which “Wi-Fi” localaccess points communicating in accordance with the IEEE 802.11 standard,is an example), WUSB, UWB, Bluetooth Low End Extension (BTLEE)/BluLite,ZigBee/IEEE 802.15.4, and UHF RFID. All of these wireless mediums havefeatures and advantages that make them appropriate for variousapplications.

More recently, manufacturers have also began to incorporate variousresources for providing enhanced functionality in WCDs (e.g., componentsand software for performing close-proximity wireless informationexchanges). Sensors and/or scanners may be used to read visual orelectronic information into a device. A transaction may involve a userholding their WCD in proximity to a target, aiming their WCD at anobject (e.g., to take a picture) or sweeping the device over a printedtag or document. Machine-readable technologies such as radio frequencyidentification (RFID), Infra-red (IR) communication, optical characterrecognition (OCR) and various other types of visual, electronic andmagnetic scanning are used to quickly input desired information into theWCD without the need for manual entry by a user.

Wireless communication devices employing the previously discussedcharacteristics may be used for a variety of applications other thanbasic voice communications. Exemplary applications for business mayinclude scheduling, word processing, spreadsheets, facsimiletransmission, contact management, etc. There is also a multitude ofapplications for the personal enjoyment of the user, such as games,instant messaging, display wallpaper, etc.

A wireless service provider may determine the current location of awireless communication device by how it is communicating on the wirelessnetwork (e.g., by identifying the cell where a cellular phone lastaccessed the network). While the benefit of being able to locate acommunication device in certain situations is apparent, such as in anemergency, the ability to provide location-related information to a userwould also be a beneficial feature. Exemplary systems now envisionedmight empower a user to determine current location using their WCD, andcombined with other applications, may be useful for route or directionfinding from a current location to another mapped location.

Current handheld location-finding systems that operate using servicessuch as the Global Positioning System (GPS) are now available on themarket. These standalone devices may provide bearings and directions toaddress locations or longitude/latitude positions. However, the bearingsand directions may only be provided relative to the moving direction ofthe GPS device. Traditional GPS receivers will not assist a user whowishes to track an object tagged with a beacon (for example, an IRbeacon on a keychain fob), or a destination that is currently unknown,such as access to public transportation or a hospital marked by an IRbeacon. While solutions are now being devised that provide for thesetracking features in a wireless communication device, just making thefunctionality available does not fully satisfy the need. A portabledevice, such as a phone or communication-enabled PDA, may be resourceconstrained (e.g., by a battery power source and small size).Conversely, a WCD that is constantly searching for a signal may consumeconsiderable power, especially if, given the shrinking size of today'sdevices, there is little room for a substantial antenna array to receivelocator signals. As a result, for a tracking application to be usefuland effective, these device limitations must be considered.

What is therefore needed is a directional and/or location finding methodand system that allows a user to track or locate a signal beacon using adirection of Arrival (DoA) estimation, while simultaneously managing thewireless communication device to optimize its performance. The DoAapplication should work in conjunction with various resources within thewireless communication device in order to provide a visualrepresentation of the relative direction towards, or location of, anobject, place, etc. maintaining a broadcast beacon. The functionalityshould further utilize information from one or more sensors within thedevice to affect the behavior of the device, for example, by controllingthe DoA functionality and/or application, quality measurement of the DoAestimate, power management of the device, etc.

SUMMARY OF INVENTION

The present invention includes at least a method, device and computerprogram for enhancing the performance of a WCD executing a direction ofarrival (DoA) estimation. Performance may be improved through devicemanagement, and may include the collection of information from one ormore sensors installed within the WCD. The sensor information mayinitially be used to determine an appropriate configuration for thedevice. Further, the sensor information may also be used to affect thebehavior of the device during the DoA estimation.

The DoA estimation may, in at least one embodiment of the invention,involve determining a relative direction towards a beacon deviceemitting a locator signal. The relative direction towards the beacon maybe displayed for a user on a display within the WCD. The DoA estimationmay operate in a multitude of modes depending on the physicalorientation of the device. For example, a closed device with an externaldisplay screen may execute a DoA application that displays a directionalpointer in a compass-like fashion in order to indicate the directiontowards a target. In another scenario, a different device orientationmay activate other resources within the WCD, such as a camera. A cameraimage may be displayed on the WCD in a view-finder mode, includingdirectional indicators and a target indicia for expressing to a user thedirection to move the WCD in order to align the target with the targetindicia. Information obtained from the one or more sensors may be usedto indicate a configuration for an application, such as the applicationitself, antenna calibration vectors and a user interface configuration.

In addition, the WCD, in at least one embodiment of the presentinvention, may continue to use collected sensor information during theexecution of a DoA estimation in order to enhance the performance of theWCD. For example, power management may be implemented through motionsensors installed in the WCD. A DoA-based application tracking astationary target may conserve power by pausing a DoA estimation untilthe motion of the WCD is detected by the motion sensors. When the WCD ismoved, the updating of the DoA estimation may be resumed. Thisfunctionality may be further implemented so that a power saving mode istriggered in both the tracking WCD and in the beacon device of a target.As a result, power may be conserved in the beacon device when the WCD isnot actively performing a DoA estimation.

In a further example of the present invention, a quality level of thelocator signal may be computed and indicated on the display of a WCDduring a DoA estimation. A quality level may be determined by measuringan Azimuthal Power Spectrum (APS) for a beacon signal. A lack of aclearly dominant DoA (e.g., the locator signal appears to be arrivingfrom several directions, or the dominant DoA varies faster than expectedbased on information provided by movement sensors in the WCD) may be anindication of an erroneous DoA estimate. In a situation where thereliability of the DoA estimate seems low, action(s) may be triggeredwithin the WCD in order to prevent the user from wasting time andresources in following a false signal. For example, a DoA estimate maynot be displayed for a received signal if the quality level isdetermined to be below a threshold level.

DESCRIPTION OF DRAWINGS

The invention will be further understood from the following detaileddescription of a preferred embodiment, taken in conjunction withappended drawings, in which:

FIG. 1 discloses an exemplary short-range to long-range wirelesscommunication environment usable to describe at least one embodiment ofthe present invention.

FIG. 2 discloses a modular description of an exemplary wirelesscommunication device usable with at least one embodiment of the presentinvention.

FIG. 3 discloses an exemplary structural description of the wirelesscommunication device previously described in FIG. 2.

FIG. 4 discloses exemplary forms of location-finding and directionalsystems currently employed to determine direction and/or location.

FIG. 5 discloses an exemplary wireless communication device includingintegrated direction-finding features in the form of an antenna array inaccordance with at least one embodiment of the present invention.

FIG. 6 discloses an exemplary structural description fordirection-finding features usable for receiving a position-indicatingtransmission in accordance with at least one embodiment of the presentinvention.

FIG. 7 discloses exemplary antenna arrangements and an alternativestructural description for receiving a position-indicating transmissionin accordance with at least one embodiment of the present invention.

FIG. 8 discloses an exemplary position-indicating transmission anddifferent transmission strategies in accordance with at least oneembodiment of the present invention.

FIG. 9A discloses exemplary mechanical orientations of wirelesscommunication devices in accordance with at least one embodiment of thepresent invention.

FIG. 9B discloses a system representation of an exemplary direction ofarrival estimating subsystem in accordance with at least one embodimentof the present invention.

FIG. 10 discloses examples of coordinate systems that may be utilized inat least two applications of direction of arrival estimation inaccordance with at least one embodiment of the present invention.

FIG. 11 discloses exemplary power management schemes for a trackingdevice and/or a beacon device in accordance with at least one embodimentof the present invention.

FIG. 12 discloses an exemplary process flowchart for device managementusing sensor information during the execution of a direction of arrivalestimation in accordance with at least one embodiment of the presentinvention.

FIG. 13 discloses exemplary Azimuthal Power Spectrum diagrams and asignal quality indicator in accordance with at least one embodiment ofthe present invention.

FIG. 14 discloses a process flowchart for executing an exemplary signalquality determination in accordance with at least one embodiment of thepresent invention.

DESCRIPTION OF PREFERRED EMBODIMENT

While the invention has been described in preferred embodiments, variouschanges can be made therein without departing from the spirit and scopeof the invention, as described in the appended claims.

I. Wireless Communication Over Different Communication Networks

A WCD may both transmit and receive information over a wide array ofwireless communication networks, each with different advantagesregarding speed, range, quality (error correction), security (encoding),etc. These characteristics will dictate the amount of information thatmay be transferred to a receiving device, and the duration of theinformation transfer. FIG. 1 includes a diagram of a WCD and how itinteracts with various types of wireless networks.

In the example pictured in FIG. 1, user 110 possesses WCD 100. Thisdevice may be anything from a basic cellular handset to a more complexdevice such as a wirelessly enabled palmtop or laptop computer. NearField Communications (NFC) 130 include various transponder-typeinteractions wherein normally only the scanning device requires its ownpower source. WCD 100 scans source 120 via short-range communications. Atransponder in source 120 may use the energy and/or clock signalcontained within the scanning signal, as in the case of RFIDcommunication, to respond with data stored in the transponder. Thesetypes of technologies usually have an effective transmission range onthe order of ten feet, and may be able to deliver stored data in amountsfrom 96 bits to over a megabit (or 125 Kbytes) relatively quickly. Thesefeatures make such technologies well suited for identification purposes,such as to receive an account number for a public transportationprovider, a key code for an automatic electronic door lock, an accountnumber for a credit or debit transaction, etc.

The transmission range between two devices may be extended if bothdevices are capable of performing powered communications. Short-rangeactive communications 140 includes applications wherein the sending andreceiving devices are both active. An exemplary situation would includeuser 110 coming within effective transmission range of a Bluetooth™,WLAN, UWB, WUSB, etc. access point. In the case of Bluetooth Low EndExtension (BTLEE)/BluLite, a network may automatically be established totransmit information to WCD 100 possessed by user 110. BTLEE/BluLite maybe used for battery-powered devices, such as wireless sensors, since itspower consumption is low. A BTLEE device may use the advertisement modeto more rapidly establish the initial connection to WCD 100. This datamay include information of an informative, educational or entertainingnature. The amount of information to be conveyed is unlimited, exceptthat it must all be transferred in the time when user 110 is withineffective transmission range of the access point. This duration may beextremely limited if the user is, for example, strolling through ashopping mall or walking down a street. Due to the higher complexity ofthese wireless networks, additional time is also required to establishthe initial connection to WCD 100, which may be increased if manydevices are queued for service in the area proximate to the accesspoint. The effective transmission range of these networks depends on thetechnology, and may be from some 30 ft. to over 300 ft. with additionalpower boosting.

Long-range networks 150 are used to provide virtually uninterruptedcommunication coverage for WCD 100. Land-based radio stations orsatellites are used to relay various communications transactionsworldwide. While these systems are extremely functional, the use ofthese systems is often charged on a per-minute basis to user 110, notincluding additional charges for data transfer (e.g., wireless Internetaccess). Further, the regulations covering these systems may causeadditional overhead for both the users and providers, making the use ofthese systems more cumbersome.

II. Wireless Communication Device

As previously described, the present invention may be implemented usinga variety of wireless communication equipment. Therefore, it isimportant to understand the communication tools available to user 110before exploring the present invention. For example, in the case of acellular telephone or other handheld wireless devices, the integrateddata handling capabilities of the device play an important role infacilitating transactions between the transmitting and receivingdevices.

FIG. 2 discloses an exemplary modular layout for a wirelesscommunication device usable with the present invention. WCD 100 isbroken down into modules representing the functional aspects of thedevice. These functions may be performed by the various combinations ofsoftware and/or hardware components discussed below.

Control module 210 regulates the operation of the device. Inputs may bereceived from various other modules included within WCD 100. Forexample, interference sensing module 220 may use various techniquesknown in the art to sense sources of environmental interference withinthe effective transmission range of the wireless communication device.Control module 210 interprets these data inputs, and in response, mayissue control commands to the other modules in WCD 100.

Communications module 230 incorporates all of the communications aspectsof WCD 100. As shown in FIG. 2, communications module 230 may include,for example, long-range communications module 232, short-rangecommunications module 234 and machine-readable data module 236 (e.g.,for NFC). Communications module 230 utilizes at least these sub-modulesto receive a multitude of different types of communication from bothlocal and long distance sources, and to transmit data to recipientdevices within the transmission range of WCD 100. Communications module230 may be triggered by control module 210, or by control resourceslocal to the module responding to sensed messages, environmentalinfluences and/or other devices in proximity to WCD 100.

User interface module 240 includes visual, audible and tactile elementswhich allow the user 110 to receive data from, and enter data into, thedevice. The data entered by user 110 may be interpreted by controlmodule 210 to affect the behavior of WCD 100. User-inputted data mayalso be transmitted by communications module 230 to other devices withineffective transmission range. Other devices in transmission range mayalso send information to WCD 100 via communications module 230, andcontrol module 210 may cause this information to be transferred to userinterface module 240 for presentment to the user.

Applications module 250 incorporates all other hardware and/or softwareapplications on WCD 100. These applications may include sensors,interfaces, utilities, interpreters, data applications, etc., and may beinvoked by control module 210 to read information provided by thevarious modules and in turn supply information to requesting modules inWCD 100.

FIG. 3 discloses an exemplary structural layout of WCD 100 according toan embodiment of the present invention that may be used to implement thefunctionality of the modular system previously described in FIG. 2.Processor 300 controls overall device operation. As shown in FIG. 3,processor 300 is coupled to at least communications sections 310, 320and 340. Processor 300 may be implemented with one or moremicroprocessors that are each capable of executing software instructionsstored in memory 330.

Memory 330 may include random access memory (RAM), read only memory(ROM), and/or flash memory, and stores information in the form of dataand software components (also referred to herein as modules). The datastored by memory 330 may be associated with particular softwarecomponents. In addition, this data may be associated with databases,such as a bookmark database or a business database for scheduling,email, etc.

The software components stored by memory 330 include instructions thatcan be executed by processor 300. Various types of software componentsmay be stored in memory 330. For instance, memory 330 may store softwarecomponents that control the operation of communication sections 310, 320and 340. Memory 330 may also store software components including afirewall, a service guide manager, a bookmark database, user interfacemanager, and any communications utilities modules required to supportWCD 100.

Long-range communications 310 performs functions related to the exchangeof information over large geographic areas (such as cellular networks)via an antenna. These communication methods include technologies fromthe previously described 1G to 3G. In addition to basic voicecommunications (e.g., via GSM), long-range communications 310 mayoperate to establish data communications sessions, such as GeneralPacket Radio Service (GPRS) sessions and/or Universal MobileTelecommunications System (UMTS) sessions. Also, long-rangecommunications 310 may operate to transmit and receive messages, such asshort messaging service (SMS) messages and/or multimedia messagingservice (MMS) messages.

As a subset of long-range communications 310, or alternatively operatingas an independent module separately connected to processor 300,transmission receiver 312 allows WCD 100 to receive transmissionmessages via mediums such as Digital Video Broadcast for HandheldDevices (DVB-H). These transmissions may be encoded so that only certaindesignated receiving devices may access the transmission content, andmay contain text, audio or video information. In at least one example,WCD 100 may receive these transmissions and use information containedwithin the transmission signal to determine if the device is permittedto view the received content.

Short-range communications 320 is responsible for functions involvingthe exchange of information across short-range wireless networks. Asdescribed above and depicted in FIG. 3, examples of such short-rangecommunications 320 are not limited to Bluetooth™, WLAN, UWB and WirelessUSB connections. Accordingly, short-range communications 320 performsfunctions related to the establishment of short-range connections, aswell as processing related to the transmission and reception ofinformation via such connections.

Short-range input device 340, also depicted in FIG. 3, may providefunctionality related to the short-range scanning of machine-readabledata (e.g., for NFC). For example, processor 300 may control short-rangeinput device 340 to generate RF signals for activating an RFIDtransponder, and may in turn control the reception of signals from anRFID transponder. Other short-range scanning methods for readingmachine-readable data that may be supported by the short-range inputdevice 340 are not limited to IR communications, linear and 2-D (e.g.,QR) bar code readers (including processes related to interpreting UPClabels), and optical character recognition devices for reading magnetic,UV, conductive or other types of coded data that may be provided in atag using suitable ink. In order for the short-range input device 340 toscan the aforementioned types of machine-readable data, the input devicemay include optical detectors, magnetic detectors, CCDs or other sensorsknown in the art for interpreting machine-readable information.

As further shown in FIG. 3, user interface 350 is also coupled toprocessor 300. User interface 350 facilitates the exchange ofinformation with a user. FIG. 3 shows that user interface 350 includes auser input 360 and a user output 370. User input 360 may include one ormore components that allow a user to input information. Examples of suchcomponents include keypads, touch screens, and microphones. User output370 allows a user to receive information from the device. Thus, useroutput portion 370 may include various components, such as a display,light emitting diodes (LED), tactile emitters and one or more audiospeakers. Exemplary displays include liquid crystal displays (LCDs), andother video displays.

WCD 100 may also include one or more transponders 380. This isessentially a passive device that may be programmed by processor 300with information to be delivered in response to a scan from an outsidesource. For example, an RFID scanner mounted in a entryway maycontinuously emit radio frequency waves. When a person with a devicecontaining transponder 380 walks through the door, the transponder isenergized and may respond with information identifying the device, theperson, etc. Alternatively, a scanner may be mounted in the WCD so thatit can read information from other transponders in the vicinity.

Hardware corresponding to communications sections 310, 312, 320 and 340provide for the transmission and reception of signals. Accordingly,these portions may include components (e.g., electronics) that performfunctions, such as modulation, demodulation, amplification, andfiltering. These portions may be locally controlled, or controlled byprocessor 300 in accordance with software communications componentsstored in memory 330.

The elements shown in FIG. 3 may be constituted and coupled according tovarious techniques in order to produce the functionality described inFIG. 2. One such technique involves coupling separate hardwarecomponents corresponding to processor 300, communications sections 310,312 and 320, memory 330, short-range input device 340, user interface350, transponder 380, etc. through one or more bus interfaces (which maybe wired or wireless bus interfaces). Alternatively, any and/or all ofthe individual components may be replaced by an integrated circuit inthe form of a programmable logic device, gate array, ASIC, multi-chipmodule, etc. programmed to replicate the functions of the stand-alonedevices. In addition, each of these components is coupled to a powersource, such as a removable and/or rechargeable battery (not shown).

The user interface 350 may interact with a communications utilitiessoftware component, also contained in memory 330, which provides for theestablishment of service sessions using long-range communications 310and/or short-range communications 320. The communications utilitiescomponent may include various routines that allow the reception ofservices from remote devices according to mediums such as the WirelessApplication Medium (WAP), Hypertext Markup Language (HTML) variants likeCompact HTML (CHTML), etc.

III. Current Systems for Providing Location-Finding or DirectionalInformation

There are some examples of location-finding or direction-finding systemson the market today. In FIG. 4, two varieties are disclosed which mayrepresent two extremes in this technology area. These two technologieshave been implemented to serve very different purposes, and as such,have different strengths and weaknesses.

Global positioning systems may deliver a precise geographic location(e.g., latitude and longitude measurement) to a user. Traditionally,these systems have been mounted in vehicles, but now smaller compactversions are available that may be carried by a pedestrian. Thesesystems use satellites 400 or terrestrial radio networks 410 todetermine the location of a receiver in global coordinates, such aslongitude and latitude. The obvious advantage of these systems is theirability to determine the absolute location of a GPS device. Mostcommercial devices may figure the correct position of a person within afew meters.

However, while these systems deliver global location information, thereare some limitations to this technology. GPS is only usable outside dueto the need to receive a signal from satellite 400. Network assisted GPS(AGPS) systems also have limited indoor coverage, but the performance istypically not adequate. Precision can be intentionally limited bygovernment regulation due to security concerns regarding how a locationdevice may be maliciously used if too accurate. GPS positioning signalsare also subject to multipath (reflection) or environmentalinterference, especially in dense urban environments, which tends tocause location determining errors. In order to correct this problem,differential systems may be employed combining both satellite 400 andground based systems 410, however, these systems are more costly tooperate, the additional cost of which may be passed on to the consumers.Further, the software required to implement GPS directional systems maybe complex, requiring substantial hardware support in order to functionproperly.

On the other end of the spectrum is single antenna radio location basedonly on signal strength. Tracking device 420 may be tuned to thefrequency of one or more known signal emitters. In the simplestimplementation an omnidirectional antenna is used to find any targets inthe vicinity by receiving their signals, in order to indicate theirpresence and possibly the location of the tracking device. To improvethe accuracy, a unidirectional antenna on tracking device 420 may beused to measure the strength of each received signal, wherein thereception strength is indicated using a visual or audio method. The userphysically moves the device in a sweeping pattern and monitors thesignal strength indicator. The direction of strongest signal receptionis deemed to be the direction towards the target. RadarGolf™ is anexample of this type of device. Also more sophisticated direction anddistance tracking devices exist, such as Bluespan's® Ion-Kids®, whichare based on proprietary technology.

While this type of system is very economical to operate, it only haslimited applications. Tracking device 420 may locate only known objectsover relatively short range. The user of the device must physicallysweep the device back and forth in order to determine the targetdirection. There is no way to determine the absolute position of thetarget or tracking device 420 (e.g., there is no way to estimatelongitude and latitude of either tracker or target). In addition,depending on the technology, tracking device 420 is subject toelectromagnetic and environmental interference, and would not beeffective where this type of interference abounds, for example, in abuilding.

IV. A Multiple Antenna Direction of Arrival (DoA) Tracking System

At least one embodiment of the present invention employs signalsreceived on multiple antennas in a Direction of Arrival (“DoA”) signalprocessing scheme in order to determine a relative direction to a targetfrom WCD 100. In this technique, the direction of arrival of theincident signal (e.g., the position-indicating transmission) is resolvedbased on the phase and possibly amplitude differences of signalsreceived by the elements of an antenna array. In the simplest method,historically known as the Bartlett Beamformer, the normalized receivedpower in each array look direction (θ) is calculated using the followingrelationship:

$\begin{matrix}{{P(\theta)} = \frac{{a^{H}(\theta)}{{Ra}(\theta)}}{L^{2}}} & (1)\end{matrix}$Wherein in equation (1), a(θ) is a so called steering vector of thearray and R is the spatial covariance matrix of the received signal. Lis the number of elements in the antenna array. a^(H) denotes aconjugate transpose of the matrix a. The direction giving the highestpower is then assumed to be the direction of the target.

The covariance matrix R is obtained as:R=E{x(t)x ^(H)(t)}  (2)where x(t) is the vector of signals received from the antenna elementsas a function of time t.

The elements of the steering vector a(θ) are the output signals of thearray elements, when it receives a plane wave from direction θ. It isdefined as:a _(n)(θ)=g _(n)(θ)·e ^(−jkr) ^(n) ^(·u) ^(r) ^((θ))  (3)in which g_(n)(θ) is the complex radiation pattern of element n, k isthe wave number (defined as 2π/λ where λ is the wavelength at centerfrequency), r_(n) is the location vector of element n, and u_(r) is theradial vector towards the incident wave direction θ. In a simple case ofa linear array of identical and equally spaced elements the steeringvector simplifies to:a(θ)=g(θ)[1e ^(−jkd cos θ) . . . e ^(−j(L-1)kd cos θ)]^(T)  (4)in which d is the inter-element spacing of linear, equally spacedantenna elements in the array. θ is the angle between the lineconnecting the linearly located antenna elements and the incident wavedirection.

In a small handheld device the radiation patterns of the elements aretypically not identical because they are affected by the metallicchassis of the device. The elements may also be differently oriented dueto space limitations in the device. In this case, either Eq. (3) must beused, or the steering vector can also be directly measured in acalibration measurement, or it can be computed using electromagneticsimulation tools.

The DoA estimation accuracy decreases in the presence of multipathpropagation or noise. In the noisy multipath radio propagation channelthe accuracy can be increased by improving the resolution of the arraythrough increasing its size by adding more antenna elements. Inaddition, the distance between any two antenna elements in the arrayshould not exceed half a wavelength to obtain unambiguous DoA estimate.

Multipath radio propagation causes fading that can lead to rapid changesof the DoA estimates and temporary mispointings. To overcome the problemone aspect of the invention uses a tracking algorithm. It is based onkeeping a register of several DoA estimates and choosing the one withhighest average power to be selected as the actual output.

The DoA estimation algorithm calculates an Azimuth Power Spectrum (APS),e.g., the signal power received from azimuth directions. The trackingalgorithm extracts the maxima from the azimuth power spectrum. It keepstrack of e.g. the 5 strongest directions. If one of the newly extractedmaxima is close (e.g. within 10 degrees) to one of these directions,then the signal power and the direction is added to the trackeddirection. If not, the new direction is tracked. All the signal powervalues of the tracked directions are filtered using a forgetting curveand the DoA of each tracked direction is calculated using a weightedaverage of the extracted directions for this tracker. After each trackerupdate, tracked directions that are closer than e.g. 10 degrees aremerged and the number of tracked directions is reduced to the fivestrongest directions. Without using this tracking algorithm, thestrongest maximum would be chosen to be the DoA, which might lead torapid changes in the estimated DoA due to fading.

FIG. 5 discloses an exemplary WCD 100 configuration usable with thepresent invention. In addition to the elements and features alreadydisclosed in FIGS. 2 and 3, the present invention may also include anantenna array. A simplified three-dimensional transparent view of WCD100 is shown below the exemplary exterior picture of the device 100. Thetransparent three-dimensional view includes at least antennas A1-A6. Thenumber of antennas doesn't have to be six, but it can be any numberlarger than one. The placement of antennas A1-A6 may be within the outerhousing of WCD 100 to form an array such as the one shown. The array mayprovide directional field sensing that is interpreted into a directionfor display on WCD 100. Signal emitter 500 may emit aposition-indicating transmission that is receivable via the antennaarray. The placement and orientation of these antennas may allow a userto hold WCD 100 in an horizontal orientation, wherein the display facesupward towards the sky. As will be seen, this orientation lends morenaturally to a pointer display indicating direction, such as in the useof a traditional compass when orienteering.

In another example (not shown) the antenna array and/or supportcircuitry may be housed within an outside component that may beremovably attached to WCD 100. This exterior component or attachment maybe connected when user 110 wants to determine direction or location, andits connection may automatically signal WCD 100 to enter a position ordirection finding mode. It is important to note that if the antennaarray is housed in an attachable exterior unit, that the orientation ofthe exterior unit with respect to WCD 100 would be a fixed,predetermined orientation with respect to the housing of WCD 100 inorder to establish a known orientation for the antenna array. In thisway, the antenna array will always be in the same (or a known)configuration when attached to WCD 100.

FIG. 5 also includes an example display shown on WCD 100 that isviewable by user 110. This display may be implemented in differentconfigurations depending upon the application to which it is applied. Inthis example, the display shows both a list of possible target objectsand an arrow pointer. There can be one or multiple active signalemitters 500 within one area at the same time. Multiple beacons canshare the same communications medium by using a multiple access method(code, frequency or time). The “KEYS” target object is currentlyselected. This object is also represented in FIG. 5 as by signal emitter500, which may be included as a keychain connected to a set of keys.Since the keys object is selected, the WCD 100 will attempt to definethe relative direction towards the target designated as keys. Thedisplay shows the directional arrow pointing in the direction of thekeys, and gives a relative direction measurement towards the keys of−90°. As the user moves toward the selected target, WCD 100 willcontinuously measure the signal of the target device and will update thedisplay accordingly so that the arrow and the directional measurementcontinue to indicate the relative direction toward the keys.

FIG. 6 includes a structural diagram of WCD 100. Again, WCD 100 includesany and or all of the elements and features previously disclosed inFIGS. 2 and 3. In FIG. 6, additional elements and features are includedthat may be composed of stand-alone devices, or may be emulated bycombinations of hardware and software present in WCD 100. Antennas A1-A6may be coupled to antenna control switch 610. Control switch 610multiplexes the antennas so that one receiver 620 may monitor incomingtransmissions from all of the antennas. Signals received on antennasA1-A6 determine the relative direction to a target from WCD 100. Thedirection of arrival of the incident signal (e.g., theposition-indicating transmission) is resolved based on the phase andpossibly amplitude differences of the signals received by the respectiveantennas A1-A6. Control switch 610 sequentially feeds the signal fromeach antenna to the receiver 620, where the Direction of Arrival (“DoA”)signal processing operates on the signal phase and possibly amplitudeinformation to determine a relative direction to a target from WCD 100.This information is fed to receiver 620. Depending on the technologyused in the switch, for example GaAs FETs vs. PIN diodes, the switch mayoperate at different speeds. In view of present technology, it appearsthat a 10 μs scan time for all antennas is conceivable. Fast switchingtime is beneficial because it allows DoA estimation from shorttransmissions and does not set high requirements for the stationarity ofthe radio channel.

In at least one embodiment of the present invention, receiver 620 is aBluetooth™ or Bluetooth Low End Extension (BTLEE) receiver, also knownas BluLite. BTLEE is an add-on extension to the Bluetooth™ command setcomposed especially for simple devices. This specialized command setallows low end devices to communicate wirelessly with a significantlylower power requirement. BTLEE may be implemented in chip form to makeBluetooth™ implementation in low end devices more economical. The use ofBTLEE may be more appropriate for the location of personal items. ABTLEE chipset may be incorporated into a keychain or into the lining ofa wallet or garment to allow locating via wireless communication, aswill be explained below. BT/BTLEE receiver 620 receives signalsmultiplexed from Antennas A1-A6 and uses this information to determinerelative direction using DoA signal processing as previously described.The receiver may also, in some cases, receive information containedwithin the position-indicating transmission. In these cases thedetermination of direction and the reception of information carriedwithin the signal may be delayed as the primary receiver 620 attempts tomultitask both information reception and DoA determination. Thissituation may be cured by the further example disclosed in FIG. 7.

The example structural configuration of FIG. 7 separates theresponsibility of determining DoA determination and BTLEE reception intotwo separate receiving modules. Antenna A1 is directly tied to BTLEEreceiver 720 so that information may be received real-time from theposition-indication transmission for immediate decoding. As will bediscussed later, this information may include identification informationannouncing that the device is a possible target, identification of thetarget and other target related data. Dedicated DoA receiver 730 maythen be free to concentrate on deriving the time and spacingrelationship between the reception of the position-indicatingtransmission at the various antennas in the antenna array, which is usedto determine the relative direction of the object from WCD 100. Theinformation received by both devices may be synchronized, for example,by control and DoA timing information sent from BTLEE receiver 720 toDoA receiver 703. Further, both receiving devices may then forwardinformation to central processor 300 which may combine, process, andformat the information for display on WCD 100. Although FIG. 7 shows tworeceivers 720 and 730, alternate embodiments of the invention may havemore than two receivers. In other examples of the present invention,receivers may also share some components, such as a VCO or synthesizer.

FIG. 7 also discloses two exemplary antenna configurations usable in atleast one embodiment of the present invention. The antennaconfigurations 700 and 710 may be implemented to improve signalreception and directional indication in the device. The more appropriateantenna configuration will depend on a variety of factors including thesize of the device, the composition (e.g., materials, layout,complexity, etc.) of the device, the antenna radiation characteristicsrequired for each antenna, antenna spacing, etc.

V. The Directional Signal

FIG. 8 discloses the makeup of an exemplary position-indicatingtransmission and different types of position indicating signals. Signaldescription 800 includes an example frame from a BTLEE/BluLitetransmission. While BTLEE/BluLite is used for this example, any of theaforementioned communication mediums may also be applicable. Initially,the transmission must be identified as a position-indicatingtransmission. The 16 bit preamble may include a code (e.g.,1010101010101010) that is used to indicate the beginning of the packetand to synchronize the receiver. This indication allows WCD 100 to beginmeasurement so that when the 8 bit service field is transmission, one orboth of the preamble and the service field may be measured by antennasA1-A6 in WCD 100. The transmission 800 may also include identificationinformation for the position-indicating transmission device, or otherdevice target related information as will be described below.

In addition, different types of position-indicating transmissionstrategies as disclosed in FIG. 8. Remotely activated locationtransmission 802 may be employed by a target whose signal emitter 500may be limited by low power concerns. These devices, such asbattery-operated transmitters in a keychain, in a wallet, embedded in anID badge, mounted in a vehicle such as an automobile, motorcycle,scooter, bicycle or in a piece of clothing, may be activated remotely bya user as needed. For example, the device may operate in a lower poweror power conservation mode until a message is received instructing adevice to activate the position-indicating transmission signal. Thismessage may be received by any of the aforementioned wireless mediumssuch as via a Bluetooth™ message. Alternatively, signal emitter 500 mayinclude a transponder, activated by a scanning signal from WCD 100. Thisscanning signal may be, for example, a UHF RFID signal. This signal mayactivate a transponder in a 5-10 meter range, and the transponder mayrespond with a signal that can be used to determine the object'srelative position, or may in turn trigger another subsystem in signalemitter 500 to transmit the position-indicating transmission.

In 804, the relative direction towards devices that require a request toactivate may be determined. These are typically powered devices that arein the possession of another user. For example, User 110 may want tolocate a friend that user 110 believes to be in the immediate area. User110 may send a message to the friend's WCD requesting an activation of aposition-indicating transmission. This message may occur via any of thelong-range mediums (for example, via SMS) or any of the short-rangemediums previously discussed. Depending on whether the friend isfamiliar with user 110, or for other security-related reasons, thefriend may accept or deny the request to activate theposition-indicating feature in their WCD. If the friend declines, amessage is returned to WCD 100 that indicates the friend has refused thelocating request. Alternatively, the friend may accept the request,activate their location beacon and WCD 100 may receive theposition-indicating transmission. This feature may be utilized forcommercial features as well. WCD 100 may indicate that there is a taxicab in the immediate area. User 110 may send a message to the taxirequesting to hire the cab and position indication. If the taxi isalready hired or on a break, the driver may refuse the request, orignore it. On the other hand, if the driver is looking for a fare he mayaccept the request, the relative position of the taxi being displayed inWCD 100 with other relevant information such as fare information.

A third type of target includes an always active position-indicatingtransmission 806. These signal emitters may be expanded range externallypowered devices, for example, Bluetooth™ access points. WCD 100 maydisplay these position markers so that user 110 may locate desiredservices. For example, a police car may include an always activeposition-indicator so that pedestrians may find them in times ofemergency. This same example may also apply to Hospital emergency rooms.In non-emergency situations, these always-on devices 806 may indicatewireless access points wherein a user may connect to the Internet via ashort-range wireless connection. Landmarks, commuter transportation suchas buses and trains, retail establishments (restaurants and stores) andentertainment venues may also utilize always-on position-indicatingtransmission emitters to advertise their services.

VI. Sensor Integration

FIG. 9A discloses a plurality of exemplary WCDs 100 in variousmechanical orientations. In each of these examples, mechanical sensorsmay provide information on the relative orientation of two sections ofWCD 100. In at least one case, an exemplary WCD 100 is pictured at 900,wherein a sensor may be integrated into hinge 902. This sensor mayprovide information to a controller in WCD 100 regarding the orientationof the device, such as shown at 900, as to whether a flip cover of thedevice is open or closed. Further, camera 904 is also disclosed at 900.The controller of the device may make a determination, based on sensordata (collected, for example, from sensor 902) as to whether to activatecamera 904. The same device is shown in another mechanical orientationat 906. A sensor 908 located in a twist joint of WCD 100 may also relayinformation to the controller of the device in order to activate certainfeatures or modes. In this example, the information provided by sensors902 and 908, alone or in combination, may trigger the controller of theWCD shown at 906 to activate camera 904. The image information receivedby camera 904 may then be displayed on a display screen of the WCD 100.In addition, other applications and/or resources related to camera 904may be triggered by evaluating the information collected from sensors902 and/or 908.

Further examples of different devices including integrated sensors areshown at 910 and 916 in FIG. 9A. The WCD 100 shown at 910 is dividedinto at least two sections that slide laterally with respect to oneanother. The device may function in one mode when the two slidingsections are aligned. However, a sensor in the sliding mechanism 912 maydetect when the device is opened (e.g., when the two sections are movedso that they are no longer aligned). In this second orientation, thecontroller of the device may implement alternate functionality or enableresources not available in the “closed” mode. In the example at 916, acellular telephone mode may be implemented at 914 when a hinge sensor902 (similar to sensor 902 previously discussed with respect to 900)provides that the device is in a closed orientation. However, when thedevice is changed to an open orientation (as shown at 916), an internalscreen may be activated along with other resources which enableadditional functionality in the device.

FIG. 9B discloses a functional diagram of a DoA subsystem in accordancewith at least one embodiment of the present invention. WCD 100 mayinclude, along with the systems and/or modules already discussed, a DoAsubsystem 920. Control for a tracking application 922 may, for example,consist of an application in memory 330 executing on the main processor300 of WCD 100, or may include a controller local to the subsystem 920working alone, or in conjunction with, processor 300. The localcontroller may utilize information provided by a DoA estimation module926 to display direction information 924 for a user. This informationmay be displayed through user interface module 240 as previouslydescribed. The DoA estimation module 926 utilizes RF interfacecomponents 928 to receive information received via antenna array 930.These modules making up DoA subsystem 920 may work together in order toprovide a relative direction towards a target beacon. However, in thepresent invention, additional modules may also be included to furtherenhance the performance of WCD 100 while performing a DoA estimation.

The sensor feedback control section of DoA subsystem 920 includes atleast two additional modules that may coupled or integrated into thesystem. Movement and/or orientation sensors module 932 may collectinformation from sensors integrated into WCD 100 (e.g., the sensorsdescribed in FIG. 9A), and may convey this information to at least thecontrol for the tracking application 922 and/or a three-dimensional(3-D) antenna calibration matrices module 934. Controller 922 may usethis sensor information to configure and/or implement functionality toenhance the performance of WCD 100 as will be further described below.3-D antenna module 934 may use the collected sensor information todetermine the appropriate antenna calibration vectors to provide to DoAEstimation module 926. These calibration vectors allow DoA Estimationmodule 926 to configure the antenna array. The antenna configuration mayinclude, for example, from which antennas to measure received beaconsignals, and how the measurements from the active antennas will beinterpreted in order to determine direction.

FIG. 10 discloses two examples of applications wherein different antennacalibration vectors may be employed. In the first example application1000, WCD 100 may be configured in a mode allowing a user to seek atarget including a locating beacon. The orientation of WCD 100 in a“flip-phone open” mode may trigger 3-D antenna module 934 to set aspecific antenna configuration, such as an antenna calibration vectorutilizing six directional antennas sensing in a spherical-pattern matrixas shown at 1000, for use in DoA estimation. In an alternative scenario,the example disclosed at 1010 shows sections of WCD 100 in anotherrelative orientation. As previously described in FIG. 9A, informationreceived from sensors 902 and/or 908 may trigger the activation ofcamera 904. In this particular application of DoA estimation, user 110may desire to track the location of a target so that it may appear onthe display of WCD 100. User 110 may be prompted by visual indiciaappearing on the display to move WCD 100 so that camera 904 may bepointed towards the beacon of the target. As a result, a subset of theavailable antennas may be configured by 3-D antenna module 934. Thissubset may include only sensing in a two-dimensional plane (four senseddirections), which may in turn allow user 110 to position WCD 100 sothat the target appears on the display of the device while savingresources not necessary for the DoA determination. An exemplary displayfor the DoA estimation as described in example 1010 will be disclosedfurther below in FIG. 13.

VII. Examples of Power Management Modes for Tracking and Beacon Devices

The information provided by sensors integrated within WCD 100 may beutilized in a number of applications. An example of using orientationsensors to provide information used for configuring WCD 100 whenexecuting a DoA application has already been described. In anotherexample, FIG. 11 discloses how information from motion sensors withinWCD 100 may be used in a power management scheme. A case where no powermanagement is employed is disclosed in the first example on the top ofFIG. 11. In this example, transmission (TX) packets from a beacon 1100are sent out on a periodic basis. In order to receive these periodictransmissions for use in DoA determination, a tracking application mayscan 1110 continuously (as represented by a solid bar with respect to aprogressing timeline in FIG. 11). While accurate resolution may beprovided with both devices under constant operation, a consequence mayalso occur in that power is continuously consumed in both devices duringthe tracking process, which may render the DoA tracking applicationinefficient and somewhat undesirable for user 110 to employ due to thepossible draining effect on the battery life of WCD 100.

The present invention, in at least one embodiment, may employinformation provided by various sensors in WCD 100 in order to manage orconserve battery life. In the second example disclosed in FIG. 11, apower management scheme is applied to the tracking device. The targetbeacon 1100 continues to emit a signal periodically. However, motionsensors integrated in WCD 100 (e.g., in the form of a semiconductorgyroscope chip, micro motion sensor, etc.) may further be used to detectwhen WCD 100 is being moved. If WCD 100 is motionless, and the target isalso not moving, then updated directional information would not benecessary until the position of WCD 100 changes. Therefore, as disclosedin the example, the tracker application halts the DoA estimation whenmotion sensors determine that WCD 100 is stationary. At a time whenmotion resumes, the DoA application control 902 may resume the DoAestimation in order to provide updated directional information through adisplay on WCD 100. In a further example of the present invention, powermay be managed both on the tracking device and in the target beacon. Atarget beacon may be a compact, low-power device operating on batteries,so power conservation may be even more essential in this device. Asdisclosed in the third example of FIG. 11, power management is appliedin the tracking device in a similar manner as described with regard tothe second example. However, now messages (TX) may also be transmittedto the target beacon when a change in state is detected in the trackingdevice. For example, a message 1112 may be sent to alter the beaconpacket transmission period or to completely stop the target beaconsignal when WCD 100 becomes stationary. Another message 1113 to resumethe broadcast of the beacon signal may then be sent when motion is againdetected in the tracking device. Further, the devices may also agree ona sleep period for a beacon device so that WCD 100 may reset the sleepcounter with TX packet 1114 after every sleep period in the beacondevice. This avoids continuous transmission of the locator signal whilea DoA application is in sleep mode. In this manner, the target beaconmay be paused when a tracking device is not actively performing a DoAestimation, and as a result, power may be conserved in both devices.Similar messages, while not pictured, may also be sent at the start oftracking and the conclusion of tracking to similarly conserve energy inthe target beacon.

An exemplary process flow in accordance with at least one embodiment ofthe present invention is disclosed in FIG. 12. An application employingDoA estimation is initiated in step 1200. This activation may occur toan intervention by user 110, automatically due to a relative orientationof sections making up WCD 100, etc. Part of the initiation of the DoAapplication will be to retrieve orientation information from varioussensors within WCD 100 in step 1208. This information may be utilized byWCD 100 in order to appropriately configure an operational mode. Forexample, in step 1210 sensor information is read to determine whether acompass directional mode should be set such as that disclosed in FIG.10, example 1000. If the sensor information dictates this mode, then instep 1212 the DoA application, antenna calibration vectors and a userinterface mode may be set in WCD 100. Alternatively, a camera trackingmode (e.g., example 1010) may be dictated by the output of varioussensors in WCD 100 (step 1214). Accordingly, another DoA application,antenna calibration vectors and a user interface mode (e.g.,incorporating images captured by camera 904) may be set in step 1216.

As previously set forth, 1210 and 1214 are exemplary modes used for thesake of explanation in the disclosure. There is no limitation as to thenumber or type of configuration modes that may be set in WCD 100, asindicated by the dotted arrow pointing to N-th application mode in step1218 and the corresponding configuration information in step 1220. Analternate mode may include, but is not limited to, a mode that senseswhen the current orientation of WCD 100 interferes with accuratedirection determination, and as a result, may compensate for the sensedorientation by enabling, for example, a different antenna calibrationvector. A similar correction or compensation mode may be employed whenuser 110 moves WCD 100 too quickly for an accurate DoA estimation.Increased activity detected by motion sensors in WCD 100 may trigger aconfiguration that increases the speed of the DoA estimation, possiblyat the cost of other characteristics such as direction resolution orpower management in the tracking device.

A DoA determination may initiate in step 1222. The beacon signal may bereceived by one or more antennas in an antenna array within (or attachedto) WCD 100, and a DoA estimation may be converted into directionalinformation for display on the device. If a power management mode isinvoked in conjunction with a DoA application, as determined in step1226, sensor information may be collected in step 1228. If no motion isdetected in step 1230 (e.g., WCD 100 is currently stationary) then theDoA estimation is temporarily disabled in step 1232. This pause inscanning may occur in conjunction with a message being sent to thebeacon device of the target causing it to halt transmission of thelocator signal until further notice. If the movement of WCD 100 isdetected in step 1230, then in step 1234 the DoA estimation is resumedin conjunction with a message being sent to the target beacon to alsoresume the broadcast of the locator signal, if necessary.

VIII. Examples of Power Signal Quality Determination

In another aspect of the present invention, an estimated quality of areceived signal may be measured and displayed for user 110 inconjunction with directional information. In at least one embodiment ofthe present invention, this quality information may indicate to user 110a confidence level as to whether the direction being indicated is theactual direction towards the target, and in some cases, the estimationmay be used to determine whether to display any directional indicationat all for signals with a quality level below a predetermined threshold.

FIG. 13 includes three Azimuthal Power Spectrum (APS) graphs at 1300.These graphs show measured signal power levels over a 360° radius. Inthe course of DoA estimation in the present invention, the APS may becontinually measured in order to determine a signal received directlyfrom the target beacon over reflected signals due to obstructions,interferences, etc. The measurements may look for peaks (local powermaxima) that occur close together and combine these maxima as part of afiltering process. The filtering process seeks to remove reflectedsignals that may indicate incorrect directions of arrival from strongersignals that indicate the appropriate direction. If, after filteringoccurs, a single power peak (or a close grouping of power peaks) from acertain direction of arrival may be identified, then a quality indicatormay be incremented. An exemplary quality indicator 1310 (labeled “Q” inthe display) shows a confidence level in the received signal. Further, adirectional indicator 1312 may indicate a relative direction towards atarget so that an image of a target may be captured and aligned withindicia 1314 (also shown on the display). However, in cases where thereis no single power peak (e.g., there are multiple peaks that are closein power level), the quality level indicator 1310 may be reduced. Ifmultiple power level peaks have an identical power level or a powerlevel within a predetermined threshold of correspondence, a variety ofactions may be triggered in WCD 100. In at least one scenario, adirection indication may be withheld until at least one dominant powerpeak presents itself. This action may be combined with a message to theuser that the signal quality is too low to reliably indicate adirection. As more measurements are taken during a DoA determination, adominant signal may become evident, and at that point, the DoAestimation and directional indication may be resumed on the display ofWCD 100.

A process flow for a signal quality determination in accordance with atleast one embodiment of the present invention is disclosed in FIG. 14.In step 1400, an Azimuthal Power Spectrum (APS) is calculated based onsignal information received by the antenna array integrated within (orcoupled to) WCD 100. This information is then processed in step 1402 inorder to determine the local maxima. In step 1404 it is determined ifmore samples are required before filtering may occur in step 1406. Ifenough data has been collected to make a quality determination in step1404, then in step 1406 power peaks (local maxima) that are in closeproximity are merged, and the data is further filtered in order todetermine if a single dominant power peak exists. If in step 1408 asingle dominant power peak is evident, then the direction of arrival isdetermined to be from where the dominant power peak was received, and aquality indicator 1310 may be increased (if not already at maximum) instep 1410. Alternatively, if no dominant power peak is evident, then instep 1412 the quality indicator 1310 may be reduced and/or actions maybe taken until a predominant power peak is determined. These actions mayinclude taking additional samples (as indicated by the dotted arrowpointing to step 1404 in FIG. 14), preventing directional informationderived from a DoA determination from being displayed until apredominant power peak is found and/or issuing a message to user 110that the current DoA estimation is unreliable due to the low qualitylevel of the locator signal being received.

The present invention is an improvement over existing systems in that itallows for direction of arrival estimation in a wireless communicationdevice with a reduced chance of depleting the power in the device ormisleading a user due to the reception of false signals. In this way, auser may have more confidence in the directional information provided byan application employing direction of arrival estimation, and will notfear using these applications due to a perceived negative impact on theperformance of the wireless communication device.

Accordingly, it will be apparent to persons skilled in the relevant artthat various changes in form a and detail can be made therein withoutdeparting from the spirit and scope of the invention. This the breadthand scope of the present invention should not be limited by any of theabove-described exemplary embodiments, but should be defined only inaccordance with the following claims and their equivalents.

1. A method, comprising: sensing, using one or more sensors in a device,information related to a mechanical orientation of a device; configuringdirection of arrival estimation functionality in the device based on theinformation sensed by the one or more sensors; and determining adirection of arrival estimate of a received signal in the device,wherein at least one sensed condition related to the received signal isused to alter a power mode for the direction of arrival estimationfunctionality.
 2. The method of claim 1, wherein the one or more sensorsinclude at least position sensors enabled to indicate the relativeorientation of at least one section of the device to another section ofthe device.
 3. The method of claim 1, wherein the one or more sensorsinclude at least motion sensors enabled to determine when the device isbeing moved.
 4. The method of claim 1, wherein a direction of arrivalestimate includes determining the direction of arrival of the signalusing an array of directional antennas coupled to the device, andfurther indicating the relative direction towards the source of thesignal on a user interface in the device.
 5. The method of claim 4,wherein configuring the direction of arrival estimation functionality inthe device based on the information sensed by the one or more sensorsincludes selecting at least a direction of arrival application program,antenna calibration vectors for the antenna array and a display mode forthe user interface.
 6. The method of claim 1, wherein at least onesensed condition related to the received signal is signal quality. 7.The method of claim 1, wherein at least one sensed condition related tothe received signal is a change, or lack of change, in position of thesource of the received signal.
 8. The method of claim 1, whereinaltering the power mode of the direction of arrival estimationfunctionality includes at least one of putting direction of arrivalestimation functionality in the device into a power conservation mode ordisabling the direction of arrival estimation functionality.
 9. Adevice, comprising: one or more sensors; at least one direction ofarrival estimation module; and a processor coupled to the one or moresensors and the at least one direction of arrival estimation module, theprocessor being configured to: sense, using the one or more sensors,information related to a mechanical orientation of the device; configurethe at least one direction of arrival estimation module in the devicebased on the information sensed by the one or more sensors; anddetermine a direction of arrival estimate of a received signal in thedevice, wherein at least one sensed condition related to the receivedsignal is used to alter a power mode for the direction of arrivalestimation module.
 10. The device of claim 9, wherein the one or moresensors include at least position sensors enabled to indicate therelative orientation of at least one section of the device to anothersection of the device.
 11. The device of claim 9, wherein the one ormore sensors include at least motion sensors enabled to determine whenthe device is being moved.
 12. The device of claim 9, wherein adirection of arrival estimate includes determining the direction ofarrival of the signal using an array of directional antennas coupled tothe device, and further indicating the relative direction towards thesource of the signal on a user interface in the device.
 13. The deviceof claim 12, wherein configuring the direction of arrival estimationmodule in the device based on the information sensed by the one or moresensors includes selecting at least a direction of arrival applicationprogram, antenna calibration vectors for the antenna array and a displaymode for the user interface.
 14. The device of claim 9, wherein at leastone sensed condition related to the received signal is signal quality.15. The device of claim 9, wherein at least one sensed condition relatedto the received signal is a change, or lack of change, in position ofthe source of the received signal.
 16. The device of claim 9, whereinaltering the power mode of the direction of arrival estimation moduleincludes at least one of putting direction of arrival estimationfunctionality in the device into a power conservation mode or disablingthe direction of arrival estimation module.
 17. A computer programproduct comprising computer executable program code recorded on anon-transitory computer readable storage medium, the computer executableprogram code comprising: code configured to cause a device to sense,using one or more sensors, information related to a mechanicalorientation of the device; code configured to cause the device toconfigure direction of arrival estimation functionality based on theinformation sensed by the one or more sensors; and code configured tocause the device to determine a direction of arrival estimate of areceived signal in the device, wherein at least one sensed conditionrelated to the received signal is used to alter a power mode for thedirection of arrival estimation functionality.
 18. The computer programproduct of claim 17, wherein the one or more sensors include at leastposition sensors enabled to indicate the relative orientation of atleast one section of the device to another section of the device. 19.The computer program product of claim 17, wherein the one or moresensors include at least motion sensors enabled to determine when thedevice is being moved.
 20. The computer program product of claim 17,wherein a direction of arrival estimate includes determining thedirection of arrival of the signal using an array of directionalantennas coupled to the device, and further indicating the relativedirection towards the source of the signal on a user interface in thedevice.
 21. The computer program product of claim 20, whereinconfiguring the direction of arrival estimation functionality in thedevice based on the information sensed by the one or more sensorsincludes selecting at least a direction of arrival application program,antenna calibration vectors for the antenna array and a display mode forthe user interface.
 22. The computer program product of claim 17,wherein at least one sensed condition related to the received signal issignal quality.
 23. The computer program product of claim 17, wherein atleast one sensed condition related to the received signal is a change,or lack of change, in position of the source of the received signal. 24.The computer program product of claim 17, wherein altering the powermode of the direction of arrival estimation functionality includes atleast one of putting direction of arrival estimation functionality inthe device into a power conservation mode or disabling the direction ofarrival estimation functionality.
 25. A method, comprising: sensing,using one or more sensors in a device, information related to a stateand/or alignment of the device; configuring the device based on theinformation sensed by the one or more sensors; determining a directionof arrival estimate of a received signal in the device, wherein sensedconditions relating to the state and/or alignment of the device areutilized to affect the behavior of the device while determining thedirection of arrival estimate; and if a power management mode isenabled, performing power management that disables the direction ofarrival estimate determination when one or more sensors detect that thedevice is stationary.
 26. A device, comprising: one or more sensors; atleast one direction of arrival estimation module; and a processorcoupled to the one or more sensors and the at least one direction ofarrival estimation module, the processor being configured to: sense,using one or more sensors, information related to a state and/oralignment of the device; configure the device based on the informationsensed by the one or more sensors; determine a direction of arrivalestimate of a received signal in the device, wherein sensed conditionsrelating to the state and/or alignment of the device are utilized toaffect the behavior of the device while determining the direction ofarrival estimate; and if a power management mode is enabled, performpower management that disables the direction of arrival estimatedetermination when one or more sensors detect that the device isstationary.
 27. A computer program product comprising computerexecutable program code recorded on a non-transitory computer readablestorage medium, the computer executable program code comprising: codeconfigured to cause a device to sense, using one or more sensors,information related to a state and/or alignment of the device; codeconfigured to cause a device to configure the device based on theinformation sensed by the one or more sensors; code configured to causea device to determine a direction of arrival estimate of a receivedsignal in the device, wherein sensed conditions relating to the stateand/or alignment of the device are utilized to affect the behavior ofthe device while determining the direction of arrival estimate; and codeconfigured to cause a device to, if a power management mode is enabled,perform power management that disables the direction of arrival estimatedetermination when one or more sensors detect that the device isstationary.